Convergence assembly for color television picture tubes

ABSTRACT

THE ILLUSTRATED CONVERGENCE ASSEMBLY IS MOUNTED ON A SUPPORTING BOARD HAVING AN OPENING THEREIN FOR RECEIVING THE NECK OF A COLOR TELEVISION PICTURE TUBE. A PLURALITY OF CONVERGENCE UNITS ARE SECURED TO THE BOARD, WHICH MAY TAKE THE FORM OF A PRINTED CIRCUIT BOARD. EACH CONVERGENCE UNIT COMPRISES A PAIR OF BOBBINS HAVING CONVERGENCE COILS MOUNTED THEREON. THE BOBBINS ARE SECURELY FASTENED TO SAID BOARD. EACH BOBBIN HAS AN AXIAL OPENING IN WHICH A MAGNETIC CORE MEMBER IS SLIDABLY MOUNTED. THE CONVERGENCE UNIT COMPRISES SPRING MEANS FOR BIASING THE CORE MEMBERS INWARDLY SO THAT THE INNER ENDS OR POLES OF THE CORE MEMBERS ARE BIASED AGAINST THE NECK OF THE PICTURE TUBE. IN THIS WAY, THE CORE MEMBERS ARE ALWAYS PRESSED FIRMLY AGAINST THE NECK OF THE PICTURE TUBE DESPITE VARIATIONS IN THE SIZE OF THE NECK. SUCH SPRING MEANS PREFERABLY TAKE THE FORM OF A BOW SPRING HAVING END PORTIONS DISENGAGEABLY MOUNTED ON THE BOBBINS. THE BOW SPRING HAS A FLEXIBLE CENTRAL PORTION WHICH DEVELOPS THE INWARD BIASING FORCE ON THE CORE MEMBERS. A ROTATABLE PERMANENT MAGNET IS PREFERABLY INTERPOSED BETWEEN THE BOW SPRING AND THE CORE MEMBERS.

United States Patent [191 Anthony et al.

[4 June 18, 1974 CONVERGENCE ASSEMBLY FOR COLOR TELEVISION PICTURE TUBES [76] Inventors: Albert M. Anthony; Richard J. Anthony, both of 16 Charles St., Bangor, Mich. 49013 [22] Filed: Jan. 22, 1973 [21] Appl. No.: 325,349

[52] US. Cl 335/210, 335/212 [51] Int. Cl. H0lf 7/00 [58] Field of Search 335/210, 212, 213; 313/76, 313/77 [56] References Cited UNITED STATES PATENTS 3,138,730 6/1964 Heuer et a1. 335/212 X 3,348,177 10/1967 Wood 335/213 3,496,501 2/1970 Harten et al 313/77 X 3,555,473 1/1971 Fi glewicz et a1 3l3/77 X Primary ExaminerGeorge Harris [57] ABSTRACT The illustrated convergence assembly is mounted on a supporting board having an opening therein for receiving the neck of a color television picture tube. A plurality of convergence units are secured to the board, which may take the form of a printed circuit board. Each convergence unit comprises a pair of bobbins having convergence coils mounted thereon. The bobbins are securely fastened to said board. Each bobbin has an axial opening in which a magnetic core member is slidably mounted. The convergence unit comprises spring means for biasing the core members inwardly so that the inner ends or poles of the core members are biased against the neck of the picture tube. In this way, the core members are always pressed firmly against the neck of the picture tube despite variations in the size of the neck. Such spring means preferably take the form of a bow spring having end portions disengageably mounted on the bobbins. The bow spring has a flexible central portion which develops the inward biasing force on the core members. A rotatable permanent magnet is preferably interposed between the bow spring and the core members.

14 Claims, 9 Drawing Figures PAIEmEnJum I 3.818.395

1 Fm 9 f g CONVERGENCE ASSEMBLY FOR COLOR TELEVISION PICTURE TUBES This invention relates to a convergence assembly for a color television picture tube of the type having a plurality of electron beams, usually three in number, for the primary, colors blue, green and red.

In picture tubes of this type, the beams are converged upon a shadow mask spaced behind the fluorescent screen of the tube. The mask has a large number of openings through which the electron beams pass before they impinge upon blue, green and red phosphor dots on the fluorescent screen. By virtue of the convergence of the beams, all three beams pass through the same opening in the mask at any given time. As the beams are scanned across the fluorescent screen, the beams pass through the successive openings in the mask.

A convergence assembly usually conprises static convergence adjusting devices for initially converging the beams at the center of the screen and dynamic convergence devices for maintaining the convergence as the beams are scanned across the screen. The dynamic convergence devices usually comprise convergence coils which are supplied with convergence signals related to the scanning signals. The convergence coils produce variable magnetic fields which correct the deflection of the three beams so that convergence is maintained.

One object of the present invention is to provide a convergence assembly which is particularly well adapted to be mounted on a printed circuit board which may also carry the components employed to develop the convergence signals.

A further object is to provide such a convergence assembly which is arranged in a new and advantageous manner so as to accommodate variations in the size of the neck of the picture tube so that the convergence assembly will fit snugly against the neck despite variations in the size of the neck.

To achieve these objects, the convergence assembly preferably comprises a plurality of convergence units mounted on the supporting board, which may have an opening to receive the neck of the tube. The convergence units are spaced at intervals around such opening. Generally, there are either two or three convergence units.

Each convergence unit preferably comprises a pair of bobbins having convergence coils mounted thereon. The bobbins are fixedly mounted on the supporting board. Magnetic core members are slidably mounted in openings formed in the bobbins. The magnetic core members have inner end or pole portions which are biased against the neck of the picture tube by spring means which are capable of flexing to accommodate variations in the diameter of the neck. Thus, the magnetic core members are always firmly pressed against the neck of the tube despite any such variations.

Preferably, the spring means take the form of a bow spring having end portions disengageably mounted on the bobbins. The flexible central portion of the bow spring develops a force which biases the core members inwardly. An adjusting member is preferably interposed between the bow spring and the coremembers. Such adjusting member may be in the form of a rotatable permanent magnet which produces an initial magnetic flux through the core members. The polarity and FIG. 1 is a diagrammatic elevational section showing a convergence assembly to be described as an illustrative embodiment of the present invention, such assembly having three equally spaced convergence units.

FIG. 2 is an elevational section similar to FIG. 1. but illustrating a convergence assembly which has only two convergence units.

FIG. 3 is a plan view partly in section along the broken line 3-3 in FIG. 1.

FIG. 4 is a side elevation of one of the convergence units taken generally as indicated by the line 44 in FIG. 1.

FIG. 5 is a fragmentary enlarged perspective view showing details of the bobbins and convergence coils.

FIG. 6 is an enlarged elevation of one of the convergence units partly in longitudinal section. FIG. 7 is an exploded elevational view showing one of the convergence units in a partially disassembled condition.

FIG. 8 is a top plan view taken generally as indicated by the line 88 in FIG. 6.

FIG. 9 is a bottom plan view taken generally as indicated by the line 99 in FIG. 6.

It will be seen that FIG. 1 illustrates a convergence assembly 10 comprising a supporting board or plate 12, which preferably takes the form of a printed circuit board.

As shown, the board 12 is formed with an opening 14 to receive the neck 16 of a color television picture tube. A plurality of electron beams are employed in the picture tube. In this case, there are three electron beams designatedB, G and R to indicate blue, green and red. The illustrated beams are in a triangular or delta pattern, but the invention is also applicable to picture tubes in which the beams are in line with one another or are in some other pattern.

The convergence assembly 10 employs a plurality of convergence units 18. In thiscase, there are three such units 18 spaced at equal intervals around the opening 14. One of the units 18 is opposite each of the electron beams B, G and R. The convergence units 18 are securely mounted on the board 12.

FIG. 2 illustrates a modified convergence assembly 20 which utilizes only two convergence units 18a and 18b which are the same mechanically as the convergence units 18 of FIG. 1, but may differ electrically in the arrangement and connection of the convergence coils. The description to follow relating to the convergence units 18 is also applicable to the convergence units 18a and b. g

It will be seen from FIGS. 3-9 that each convergence unit 18 preferably comprises a pair of bobbins or spools 22 adapted to support convergence coils 24 and 26. The bobbins 22 are preferably made of suitable insulating materials such as various resinous plastic materials. The larger convergence coils 24 are mounted directly on the bobbins 22, while the smaller convergence coils 26 are mounted on separate small bobbins 28.

It will be seen that each of the smaller coils 26 complete with its bobbin 28 fits into an enlarged opening 30 within the corresponding larger bobbin 22. The larger coils 24 are generally supplied with convergence signals related to the vertical sweep signals, while the smaller coils 26 are supplied with convergence signals related to the horizontal sweep signals.

It is preferred to fasten the bobbins 22 securely to the supporting board 12. In the illustrated construction, this is accomplished by means of prongs or lugs 32, projecting laterally from the bobbins 22. Various other fasteners could be employed. While the prongs 32 could be made of insulating material, they are preferably made of conductive material, such as metal wire, so that the prongs 32 can serve as terminals for the coils 24 and 26.

As illustrated in FIG. 3, the prongs 32 preferably extend through holes 34 in the supporting board 12. As illustrated, the prongs 32 are anchored by soldering them to conductive printed circuit elements 36 on the board 12. The soldered joints are indicated at 38. The conductive elements 36 are preferably made of copper or some other highly conductive metal bonded to the supporting board 12 and forming portions of the convergence circuit which is employed to supply the convergence signals to the coils 24 and 26. It will be understood that the coils 24 on the adjacent bobbins 22 are generally connected in series and that the ends of the series-connected coils are connected to a pair of the terminals 32. Similarly, the adjacent coils 26 are generally connected in series between the other two terminals 32.

It is preferred to provide means for connecting the adjacent bobbins 22 together so that they will be maintained in alignment. As shown in FlG. 3, interconnecting elements 40 and 42 are formed on both of the bobbins 22 and are adapted to fit together. The illustrated elements 40 are in the form of pins or lugs, while the elements 42 take the form of openings adapted to receive the pins 40.

Magnetic core members 44 are preferably provided within the coils 24 and 26 to concentrate and intensify the magnetic flux produced by the coils. As shown in FIG. 7, each of the magnetic core members 44 is generally L-shaped and is formed with longer and shorter legs 46 and 48. An axial opening 50 is formed in each of the bobbins 22 to receive the leg 46 of the corresponding core member 44 A similar opening 52 is formed in each of the smaller bobbins 28. The leg 46 is freely slidable through the openings 50 and 52. As shown, the legs 46 and the openings 50 and 52 are square or rectangular in cross section, but they could be of some other shape.

The shorterlegs 48 of the magnetic cores 44 for the adjacent bobbins 22 are assembled so that the ends of the legs 48 form a butt joint 54. If desired, the joint 54 may include a thin spacer of non-magnetic material.

The magnetic cores 44 are preferably made of a material having high magnetic permeability and low losses. For example, various ferrite materials may be employed.

The ends of the longer legs 46 on the magnetic core members 44 are preferably formed with pole portions 56 which are shaped to fit closely against the neck 16 of the television picture tube. The pole portions 56 project out of the vertical and horizontal convergence coils 24 and 26.

The shorter legs 48 of the magnetic core members 44 extend beyond the opposite ends of the coils 24 and 26. To assist in maintaining alignment between the shorter legs 48 of the adjacent core members 44, a plate or spacer 58 is preferably interposed between the bobbins 22 and the shorter legs 48. The longer legs 46 extend through openings 60 in the plate 58 which is preferably made of an insulating material such as a suitable resinous plastic material.

Resilient tabs or flanges 62 are preferably bent outwardly from the plate 58 adjacent the opening 60 to engage the magnetic core members 44. The resilient tabs 62 produce spring loading between the plate 58 and the core members 44 to take up any looseness so that the ends of the shorter legs 48 will be held together snugly at the joint 54.

It is preferred to provide a movable adjusting member in the form of a rotatable permanent magnet 64 opposite the shorter legs 48 of the adjacent core members 44. The illustrated magnet 64 is in the form of a disc having north and south poles at diametrically opposite points. The magnet 64 may be made of any suitable magnetic material such as various ferrites. It will be seen that the magnet 64 spans the joint 54 and overlaps the shorter legs 48 of the adjacent magnetic cores 44 so that the magnet 64 is capable of producing an initial magnetic flux in the cores 44.

The magnitude and direction of the initial magnetic flux can be adjusted by rotating the permanent magnet 64. To reduce friction and to regulate the effective strength of the permanent magnet 64, a spacer 66 is preferably employed between the permanent magnet 64 and the shorter legs 48 of the magnetic cores 44. The spacer 66 may be made of a suitable plastic or some other insulating material.

Each convergence unit 18 is preferably provided with spring means for resiliently biasing the magnetic core members 44 against the neck 16 of the picture tube. In this way, the cores 44 are movable within the stationary bobbins 22 against the biasing action of the spring means to accommodate tube necks of various diameters. It will be seen from FIGS. 6 and 7 that such spring means may take the form of a bow spring 68 which develops a biasing force to be exerted against the shorter legs 48 of the magnetic cores.

The illustrated spring 68 has a main or central portion 70 which engages the rotatable permanent magnet 64 so as to retain the magnet against the legs 48 with the spacer 66 therebetween. The biasing force exerted by the spring 68 is transmitted by the magnet 64 and the spacer 66 to the legs 48 of the magnetic cores 44.

Elements are preferably employed to retain the permanent magnet 64 against lateral displacement. As shown, pivot elements 72 and 74 are preferably formed on the spring 68 and the spacer 66. These pivot elements 72 and 74 are received in a pair of axial openings 76 on the opposite sides of the disc-shaped permanent magnet 64.

The ends of the bow spring 68 are preferably provided with end portions 78 which are mounted on the bobbins 22 so that the springs will exert a resilient biasing force between the bobbins and the magnetic cores 44. Preferably, the end portions 78 of the spring 68 are readily mountable on and disengageable from the bobbins 22. As shown, each end portion 78 of the spring 68 has a pair of tines or fingers 80 which are insertable outwardly into openings 82 formed in the bobbins 22. The openings 82 may be formed by T-shaped members 84 projecting from the ends of the bobbins 22. As

shown in FIG. 4, each T-shaped member 84 has a pair of flanges 86 which overlap the fingers 80 on the spring 68.

It will be seen from FIGS. 6 and 7 that the end portions 78 are in the form of legs projecting transversely from the central portion 70 of the spring 68. The fingers 80 project outwardly from the end portions 78 and are biased outwardly by the resilience of the spring 68. It is easy to mount the spring 68 on the bobbins 22 by pressing the end portions 78 inwardly so that the fingers 80 can be inserted into the openings 82 on the bobbins 22. The spring 68 can easily be removed by compressing the end portions 78 toward each other until the fingers 80 can be withdrawn from the openings 82.

The spring 68 is preferably made of spring metal, but it may be made of various other materials such as a suitable resinous plastic material. lt will be evident that the bow spring 68 exerts a biasing force upon the permanent magnet 64 and that this force is transmitted to the magnetic cores 44 by the spacer 66. The biasing force presses the pole portions 56 of the magnetic cores 44 against the neck 16 of the color television picture tube. The spring 68 has the ability toyield so as to accommodate a considerable variation in the diameter of the neck 16. Within the range of movement afforded by the spring 68,- the magnetic cores 44 are firmly pressed against the neck 16.

We claim:

l. A convergence assembly for a plural beam color television picture tube,

comprising a supporting board having an opening therein for receiving the neck of the picture tube,

and a plurality of convergence units mounted on said board and spaced around said opening,

each of said convergence units comprising a pair of adjacent bobbins,

a plurality of convergence coils fixedly mounted on said bobbins,

mounting means for fixedly securing said bobbins to said board,

each of said bobbins having an axial opening therein,

a plurality of magnetic core members made of magnetic material and slidably received in said axial openings in said bobbins,

said core members having pole end portions projecting from the inner ends of said bobbins and engageable with the neck of the picture tube,

and spring means exerting resilient forces between said bobbins and said core members and thereby biasing said core members inwardly relative to said bobbins into engagement with the neck of the picture tube.

2. A convergence assembly for a plural beam color television picture tube,

comprising a supporting board having an opening therein for receiving the neck of the picture tube,

and a plurality of convergence units mounted on said board and spaced around said opening,

each of said convergence units comprising a pair of adjacent bobbins,

a plurality of convergence coils mounted on said bobbins,

mounting means for fixedly securing said bobbins to said board, each of said bobbins having an axial opening therein,

a plurality of magnetic core members made of magnetic material and slidably received in said axial openings in said bobbins,

said core members having pole end portions projecting from the inner ends of said bobbins and engageable with the neck of the picture tube,

and spring means for biasing said core members inwardly relative to said bobbins into engagement with the neck of the picture tube,

said spring means being connected to said bobbins to provide a resilient biasing force between said bobbins and said core members.

3. A convergence assembly according to claim 2,

in which said spring means comprises springs mounted on said bobbins and developing biasing forces against the respective core members.

4. A convergence assembly according to claim 3,

in which said springs are in the form of bow springs having end portions mounted on said bobbins,

said bow springs having respective flexible central portions for developing the biasing forces on said core members. 7

5. A convergence assembly according to claim 4,

including a movable adjusting member disposed between said central portion of each bow spring and each of said core members.

6. A convergence assembly according to claim 5,

in which each adjusting member is in the form of a rotatable permanent magnet for producing an initial magnetic flux through each of said core members.

7. A convergence assembly according to claim 6,

in which each bow spring has means for rotatably retaining and guiding the corresponding rotatable permanent magnet.

8. A convergence assembly according to claim 6,

in which each rotatable permanent magnet has an axial opening,

each bow spring having a guide elementslidably received within said axial opening in the corresponding permanent magnet.

9. A convergence assembly according to claim 4,

in which said bobbins and said end portions of each bow spring have disengageably interlocking elements for removably retaining said bow spring on said bobbins.

10. A convergence assembly according to claim 9,

in which said interlocking elements comprise fingers on said end portions of each bow spring and formations on said bobbins to provide openings for receiving said fingers,

the resiliency of said bow spring being effective to retain said fingers in said openings.

11. A convergence assembly for a plural beam color television picture tube,

comprising a supporting board having an opening therein for receiving the neck of the picture tube,

and a plurality of convergence units mounted on said board and spaced around said opening,

each of said convergence units comprising a pair of adjacent bobbins,

a plurality of convergence coils mounted on said bobbins,

mounting means for fixedly securing said bobbins to said board,

each of said bobbins having an axial opening therein,

12. A convergence assembly according to claim 11,

in which said board has metallic elements forming a printed circuit thereon,

said prongs being soldered to said metallic elements around said openings in said board,

said prongs affording conductive terminals connected to the ends of said coils.

13. A convergence assembly according to claim 12,

in which said bobbins have interengageable connector elements extending therebetween. 14. A convergence assembly according to claim 13,

in which said'connector elements comprise pins projecting from said bobbins and receptacle openings for receiving said pins. 

